Anti-biotech forces turned out in Kansas on Tuesday to argue against a state plan that would limit how dairy products free from artificial hormones can be labeled.

The Kansas Department of Agriculture held its final hearing on the matter Tuesday morning, considering a regulation that would ban dairy product labels from stating the product as "rBST free." The law would take effect in January 2010.

In addition to banning "rBST-free" claims, the rule would require that labels declaring products to have been derived from cows not supplemented with the growth hormone to carry companion disclaimers saying "the FDA has determined that no significant difference has been shown between milk derived from rBST-supplemented and non-rBST-supplemented cows."

The move comes at a time when consumer and retailer opposition to injecting dairy cows with added growth hormones is on the rise.

Recombinant bovine somatotropin (rBST) is a synthetic growth hormone injected into cows to increase their milk production, that some fear harm to animal and human health, including links to cancer.

Biotech backers have been fighting back, arguing that artificial hormones help cows produce more milk, do not create health problems for the animals or humans and argue that labels making a distinction needlessly confuse consumers when there is no discernible difference in products derived from cows that receive the hormones and those that do not.

"We simply want labels to not be misleading," said Kansas Agriculture Department spokeswoman Lisa Taylor

But opponents claim there are human and animal health risks associated with the artificial growth hormones and they say consumers have the right to know about the products they buy.

"This would make a truthful claim illegal and violate the first amendment," said Consumers Union senior scientist Michael Hansen, who testified at the Kansas hearing Tuesday.

A coalition of more than 90 groups representing dairy farmers, consumers groups, farm, agricultural and environmental organizations, food processors and retailers submitted a letter to Kansas Governor Kathleen Sebelius to oppose the new rules.

The move by Kansas comes after Ohio was sued over a similar measure this summer. A ruling in that case is still pending.

St. Louis-based Monsanto Co, a leading developer of biotech crops, had been the sole producer of the artificial hormone supplement, which it branded as Posilac. The supplement is produced through recombinant DNA technology.

The company began selling FDA-approved Posilac in 1994 as a tool for boosting milk production in cows but sold the unit in October to Eli Lilly and Co for $300 million.